A product to be sold to a customer may include several items contained within a complete package. An item inside the complete package may itself have its own packaging. In a distribution center, items are often hand-picked and placed for packaging. Robotic methods used for packaging are also known, and typically involve a positioning system having an attached robotic arm for picking and placing the items.
As shown in FIG. 1, a conventional pick-and-place apparatus may include a robotic arm 100 having a gripping mechanism 102 for picking and placing an item 104. Here, item 104 must be oriented in a vertical orientation for gripping mechanism 102 to grip item 104, since gripping mechanism 102 typically has a small gripping width 106. The vertical orientation required may result in pickup errors since a gripping area 108 of item 104 may be small and therefore difficult to grip accurately. In addition, when moving item 104 swiftly in a horizontal direction, item 104 may swing or sway, resulting in potential placement errors. If item 104 is moved more slowly to help eliminate this problem, efficiency of the pick-and-place method is reduced.
As shown in FIG. 2, a conventional vacuum pick-and-place apparatus may include a vacuum coupler 200 for picking and placing an item 202. Unfortunately, if item 202 consists of an object 204 within a package 203, where package 203 includes a main housing 206 and a cover 208, package 203 may undesirably open during pickup as shown in FIG. 3. Package 203 may open since vacuum coupler 200 picks up item 202 by cover 208 while the weight of object 204 rests on main housing 206. Package 203 may be sealed, but this adds an additional step to the packaging process, thereby increasing the required packaging time.
Conventional magnetic pick-and-place methods are known for picking and placing items having a ferrous content. However, as the speed of the pick-and-place method is increased, the required size of a permanent magnet to hold the item after pickup becomes quite large and impractical. A large magnet having a strong magnetic strength for pickup and fast positioning becomes a heavy drag on the positioning system and may further become an interference to other items or nearby electrical circuitry. In addition, a smaller item may be positioned inaccurately on a large magnet (since the large magnet may have a large magnetic surface) which may result in placement errors.
Combined vacuum and magnetic pick-and-place tools are known, but with these tools it may be difficult to pick and place items that are small, do not have planar surfaces, or require a high degree of placement accuracy. In addition, such conventional tools are inflexible to the varying shapes, sizes, and pickup needs of different items.
Accordingly, there is a resulting need for an accurate and efficient pick-and-place method and apparatus for picking and placing various items.